The present invention relates to a zeolite-substrate composite comprising a patterned zeolite layer and a method of preparation of the same. More specifically, the present invention relates to a method for the preparation of a zeolite-substrate composite comprising a patterned zeolite monolayer or multilayer on a substrate, which comprises forming a pattern of a linking compound on the substrate by binding a linking compound on the substrate surface followed by a selective irradiation with UV ray thereon, or by a selective coating on a portion of the substrate surface with a linking compound or a blocking compound such as octadecyltrichlorosilane, or by a selective deposition of a metal such as platinum on the substrate surface followed by binding a linking compound thereon, and combining selectively zeolite or zeotype molecular sieve (hereinafter, referred as to xe2x80x9czeolitexe2x80x9d or xe2x80x9cmolecular sievexe2x80x9d) along with said pattern, wherein said substrate is selected from a group consisting of a substance having surface hydroxyl groups, a metal capable of being reacted with thiol group (xe2x80x94SH) or amino group (xe2x80x94NH2) and a polymeric material having various surface functional groups. The present invention also relates to the zeolite-substrate composite prepared thereby.
Molecular sieves including zeolite are important materials, which have been employed widely in the household item level and the industrial field. Zeolite generally presents in the form of fine powder, which gives both advantages and disadvantages for using zeolite. Combining those zeolite particles firmly with various substrates through chemical bond, a wide industrial applicability of zeolite can be expected.
Further, it can be said that it is significant to adjust the zeolite so as to have a uniform orientation to the substrate as it can induce new physical properties expectedly. Still further, if zeolite particles are combined to the substrate surface so as to have a selective and/or uniform orientation, novel characteristics that have never been found in the conventional material would be expected and an epoch-making development may be achieved.
xe2x80x9cZeolitexe2x80x9d is a generic name of crystalline aluminosilicate, which constitutes the pore skeleton of zeolite molecules and bears an anionic charge for each aluminum atom. Cations for offsetting such anion charges are present within the pore space and the remaining pore space is filled with water. The three dimensional pore structure of the zeolite molecule varies depending on the shape and size of the pore, and the pore diameter is usually determined by size of the molecule. Therefore, based on the shape and size of the pore, zeolite has a shape selectivity for a molecule entering into the pore. In this connection, zeolite is called as a molecular sieve.
Zeolite (or molecular sieve) or analogous molecular sieves (hereinafter, referred to as zeolite or its analogs) show diverse chemical and physical properties depending on its chemical composition, structure, pre-treatment method, etc. Especially, modified zeolite in which protons are replaced with other cations is widely used as a cracking catalyst of crude oil in the petrochemical industry, thanks to its resistance to high temperature. Further, zeolite is widely used as a water-absorbing drying agent, adsorbent, gas-purifying agent, ion exchanger, additives for detergent, soil improving agent or the like. An extensive study is now being made on its application as a sensor carrier.
Meanwhile, there are known many other zeolite-like molecular sieves (or zeotype molecular sieves) wherein a part or all of silicon (Si) and/or aluminum (Al) atoms constituting the structural skeleton of zeolite molecule are replaced with other elements. For example, a mesoporous silica (MCM-series mesoporous silica and silicalite, etc.) in which aluminum atoms are completely eliminated, an alpo(AlPO4)-type molecular sieve in which silicon atoms are replaced with phosporous atoms, and other molecular sieve or its analog wherein skeleton metal atoms are partly replaced with various metal atom such as Ti, Mn, Co, Fe, Zn, etc., have been developed and widely used.
For better utilization of zeolite or its analogs, studies have been carried out to develop methods of attaching zeolite particles to the surface of substrates such as glass, ceramics, polymeric materials, metal, etc. [L. C. Boudreau, J. A. Kuck, M. Tsapatsis, J Membr. Sci. 1999, 152, 41-59; Z. Li, C. Lai, T. E. Mallouk, Inorg. Chem. 1989, 28, 178-182; L. C. Boudreau, J. A. Kuck, M. Tsapatsis, J. Membr. Sci. 1999, 152, 41-59; J. C. Jansen, D. Kashchiev, A. Erdem-Senataler, Stud. Surf, Sci. Catal, 1994, 85. 215-250; R. Althoff, K. Unger, F. Shuff, Microporous Mater, 1994, 2, 557-562].
However it is not easy to perfectly control the thickness and orientation of a zeolite monolayer through conventional methods. The inventors have developed a simple and economic method for the preparation of a composite of substrate-linking compound-zeolite by chemically changing the surface of the substrate or zeolite by using a linking compound having functional groups capable of reacting with the substrate or zeolite, respectively. [See: PCT/KR00/01001 with claiming a priority based on Korean Patent Application No. 2000-19667 (filed on Apr. 14, 2000)].
On the other hand, numerous studies have been carried out in respect of the formation of the pattern on the surface of substrates such as glass, ceramics, polymeric materials and metal. As to conventionally known methods for forming a pattern, the following three methods can be exemplified basically.
The first method is a selective irradiation wherein UV ray is irradiated with a photomask to selectively form a pattern. The second method is a stamping method wherein a pattern is previously prepared onto a cast by using polydimethylsiloxane (PDMS), a linking compound or a blocking compound such as octadecyltrichlorosilane is applied onto the cast, and said cast is stamped onto the substrate to form said pattern on the substrate. The third method is a selective metal deposition wherein a metal grid is stuck to a substrate and a deposited layer of a metal such as platinum is selectively formed on the substrate to form a pattern.
As set forth herein above, such technology wherein a surface is modified by forming a pattern on a substrate so that the chemical reactivity of the surface of the substrate varies along the pattern formed on said substrate is well known. There are many technical difficulties in modifying the surface of zeolite so as to have a chemical reactivity to combine the zeolite particles chemically onto a substrate.
The inventors have already achieved a great development of the chemical procedure by modifying a chemical reaction that happens in a solution state so that it can happen at the surface of a material. Further, the inventors have extensively studied in order to produce various composites by utilizing the methods thus developed.
As a result, the inventors have developed a method for the formation of a patterned monolayer or multilayer of zeolite having an excellent durability and orientation, which comprises forming a pattern on the substrate by means of UV ray, a blocking compound, a metal (e.g., platinum) deposition, etc. and chemically combining of zeolite onto the patterned surface of the substrate.
As set forth hereinabove, it has been well known to modify the surface so as to the different chemical reactivity along the pattern by forming a pattern thereon by means of UV ray, a linking or blocking compound (e.g., octadecyltrichlorosilane), a metal (e.g., platinum) deposition, etc. However, it has never been reported to form a patterned zeolite layer on surface-modified substrate.
It is now found that, when the method described in said Korean Patent Application No.2000-19667 filed by the inventors, i.e., when the method of combining zeolite to a substrate via a chemical bonding is employed, it is possible to laminate on a substrate on which a pattern has been formed a zeolite layer along the pattern formed on the substrate, to laminate not only a monolayer but also a multilayer, and to easily and diversely control the shape and material (zeolite type) in each layer.
The present invention relates to a method for the preparation of a zeolite-substrate composite, namely a composite of substrate-linking compound-zeolite comprising a patterned zeolite monolayer or multilayer, which comprises forming a pattern of a linking compound on the substrate by binding a linking compound on the substrate surface followed by a selective irradiation with UV ray thereon, or by a selective coating on a portion of the substrate surface with a linking compound or a blocking compound such as octadecyltrichlorosilane, or by a selective deposition of a metal such as platinum on the substrate surface followed by binding a linking compound thereon, and combining selectively zeolite along with said pattern, wherein said substrate is selected from a group consisting of a substance having surface hydroxyl groups, a metal capable of being reacted with thiol group (xe2x80x94SH) or amino group (xe2x80x94NH2) and a polymeric material having various surface functional groups.
Accordingly, the first object of the present invention is to provide a method for the preparation of a zeolite-substrate composite, namely a composite of substrate-linking compound-zeolite comprising a patterned zeolite monolayer or multilayer, characterized in that it comprises (i) combining a linking compound onto the surface of substrate, (ii) modifying the linking compound combined to the substrate or the functional group thereof by irradiating UV ray through a photomask having a pattern, (iii) selectively forming a zeolite layer on the area to which UV ray is irradiated or the area to which UV ray is not irradiate, and (iv) optionally performing a calcination.
In the above method of the first object, after removing the portion to which UV ray is irradiated of the portion to which UV ray is not irradiated, a zeolite layer may be formed.
The second object of the present invention is to provide a method for the preparation of a zeolite-substrate composite, namely a composite of substrate-linking compound-zeolite comprising a patterned zeolite monolayer or multilayer, characterized in that it comprises (i) combining a linking compound to a part of the surface of the substrate so as to have a predetermined pattern and then combining a blocking compound to the remaining surface of the substrate, or combining a blocking compound to a part of the surface of the substrate so as to have a predetermined pattern and then combining a linking compound to the remaining surface of the substrate, (ii) forming a zeolite layer on the area to which the linking compound is combined, and (iii) optionally performing a calcination.
In the above method of the second object, the linking compound or blocking compound can be coated on a part of the substrate surface by the stamping method.
The third object of the present invention is to provide a method for the preparation of a zeolite-substrate composite, namely a composite of substrate-linking compound-zeolite comprising a patterned zeolite monolayer or multilayer, characterized in that it comprises (i) depositing a metal such as platinum onto a part of the substrate surface to form a metal layer so as to have a predetermined pattern. (ii) forming a zeolite layer by growing crystal or combining zeolite-linking compound on the remaining area, and (iii) optionally performing a calcination.
The fourth object of the present invention is to provide a patterned monolayer or multilayer of zeolite prepared by said method, wherein the type and kind of zeolite as well as the pattern style in each of the layer can be identical with or different from each other respectively.
In the present invention, it is possible to repeat each of the first, second and third methods or combination thereof in order to produce a composite of patterned zeolite multilayer.
The present invention will be illustrated in detail below.
In the present invention, the term of xe2x80x9czeolitexe2x80x9d or xe2x80x9cmolecular sievexe2x80x9d has a meaning including zeolite or molecular sieve as well as their analogs and used indiscriminately unless otherwise specified.
1. Type of the Substrate
Examples of the substrate that can be employed in the present invention are as follows:
1) materials containing hydroxyl groups on the surface, selected from a group consisting of oxides or mixed oxides of metals and non-metals such as silicon, aluminum, titanium, tin, indium, etc., which can be used alone or in a mixture, for example, quartz, mica, glass, ITO glass (glass deposited with indium oxide of tin), tin oxide (SnO2), and other conductive glass, silica, porous silica, alumina, porous alumina, titanium dioxide, porous titanium dioxide, silicon wafer and the likes,
2) metals capable of reacting with a thiol or amino group, such as gold, platinum, silver, copper, and the like;
3) polymers having various functional groups on their surfaces, such as PVC, a Merrifield peptide resin and the like;
4) semiconductive materials, such as selenium-zinc (ZnSe), gallium-arsenic (GaAs) and indium-phosphor (InP), and the like;
5) Natural materials of high molecular weight, which carry hydroxyl groups on their surfaces, such as cellulose, starch (e.g., amylose and amylopectin), lignin and the like; or
6) Natural or synthetic zeolite or molecular sieve analogs, as defined in below.
2. Type of Molecular Sieve
The molecular sieve, i.e., zeolite and its analogous molecular sieve that can be employed in the present invention are as follows:
1) Natural and synthetic zeolite,
2) Modified molecular sieve wherein all or a part of the silicon atoms in the zeolite skeleton are replaced with other atoms such as phosphorous (P) or the like (e.g., AlPO4, SAPO, MeAPO, MeAPSO type molecular sieve),
3) Modified molecular sieve wherein all or a part of the silicon atoms in the zeolite skeleton are replaced with other atoms such as boron (B), gallium (Ga). Titanium (Ti), etc.,
4) Molecular sieves by the combination of the above modifications of the above modifications of item 2 and 3,
5) Porous metals or silicon oxides (e.g., silicalite, MCM type porous silica, porous titanium dioxide, niobium dioxide, etc.) or mixed oxide thereof, or
6) Porous molecular sieves prepared with any other elements alone or in a mixture.
3. Type of Linking Compound
The linking compound in the present invention means the compound having functional groups capable of chemically reacting with substrates or zeolite at each of the both terminals. The functional groups capable of chemically reacting with the substrate or zeolite means a group capable of chemically binding to hydroxyl group such as, for example, trichlorosilyl group (xe2x80x94SiCl3), trimethoxysilyl group (xe2x80x94Si(CH3)3) or iscyanato group (xe2x80x94Nxe2x95x90Cxe2x95x90O) with respect to the substrate such as zeolite or glass having surface hydroxyl groups, and thiol with respect to substrates such as gold. Those compounds carrying such functional groups have been known to be capable of forming a self-assembled monolayer (SAM) when reacted with said substrate.
It is understood that a functional group capable of chemically reacting with a substrate can be determined depending on the nature (namely, the functionality) of the substrate""s surface and can be suitably selected by a person having ordinary skill in the art.
The linking compounds that can be employed in the present invention can be preferably selected from the following compounds of formula 1 to 7 or a combination thereof:
Wherein, R represents a halogen atom, C1-C4 alkoxy or alkyl group; L represents a hydrocarbon residue, e.g., substituted or unsubstituted C1-C17 alkyl, aralkyl or aryl group, which may have at least one heteroatom such as oxygen, nitrogen and sulfur; X represents a leaving group such as a halogen atom; provided that at least one of the three Rs in a SiR3 group denote a halogen or alkoxy group; Rxe2x80x2 is the same as R and the two of four R""s in MRxe2x80x24 denote a halogen or alkoxy group; M represents Si or a transition metal such as Ti or Zr; Y represents a ligand having a functional group selected from a group consisting of hydroxyl, thiol, amine, ammonium, sulfone and its salt, carboxyl acid and its salt, acid anhydride, epoxy, aldehyde, ester, acrylate, isocyanate (xe2x80x94NCO), sugar residue, double bond, triple bond, diene, diyne, alkylphosphine, alkylamine as well as a reactive functional group of various coordination compounds capable of exchanging their ligands; provided that said functional group can exist in the middle or at the terminal ends of the ligands.
The linking compound combined to the substrate or zeolite can have at least one functional group in the skeleton of the linking compound to give the secondary chemical bonding. To illustrate, when a linking compound combined to the substrate contains formyl group (xe2x80x94CHO) in the molecule and another linking compound combined to the surface of zeolite has amino group (xe2x80x94NH2) in the molecule, zeolite can combine to the substrate via a chemical linkage of linking compound-linking compound since a chemical reaction between the amino group and the formyl group can easily happen.
As illustrated above, another linking compound or a bifunctional compound can intermediate in the linkage of linking compound-linking compound, for instance the following interposition compound can be exemplified: at least a compound selected from a group consisting of fullerene (C60, C70), carbon nanotubes, xcex1,xcfx89-dialdehyde, dicarboxylic acid, dicarboxyl acid anhydride, amine-dendrimer, polyethylene imine, xcex1,xcfx89-diamine, a complex of [M(salan)] (wherein M represents Co, Ni, Cr, Mn, Fe and the like, and salan represents N,N-bis(salicylidene)ethylenediamine), and metal porphyrin derivatives.
Considering collectively the above matters, a linking compound should have at least two functional group, one for combining with the substrate and another one for chemically combining with the functional group of the other linking compound bound to the surface of the other zeolite or particles thereof. The matching or combination of the linking compound and its functional group can greatly vary and is easily achieved by a person having ordinary skill in the pertinent art depending on the necessity. Those variations and modifications are also included in the scope of the present invention if they employ the concept of the present invention.
4. Chemical Reaction of Linking Compounds with a Substrate or Zeolite
Since substrates such as glass and molecular sieves such as zeolite have hydroxyl groups on their surface as described above, they can react with linking compounds having a suitable functional group capable of reacting with hydroxyl group to form a composite of substrate-linking compound or linking compound-zeolite. Further, since some functional group can be modified or changed to a new functional group by a suitable treatment, a material having any adequate functionality on its surface can be modified through a chemical treatment so as to have new functionality. The reaction and its condition for said treatment have been publicly known in this field.
Although metals such as gold does not have hydroxyl group on the surface, it exhibit a superior reactivity to thiol group and so can be used as a substrate in the present invention owing to the remarkable reactivity to the linking compound introduced with one terminal thiol group. The compound having a one terminal thiol group can be used as a linking compound or blocking compound to the substrate of gold.
The substrate or zeolite particles are put into a container containing an organic solvent such as toluene, to which a linking compound is added and then the mixture is heated. Instead of toluene, another organic solvent such as hexane, benzene, tetrachlorocarbon, alcohol, etc. can be adequately used for the reaction. Upon the completion of reaction, the substrate is taken out and then washed with toluene. When executing such a chemical bonding onto the surface of zeolite, the vapor of the organic compound can be used sometimes to raise the chemical bonding directly. The zeolite in the dispersed liquid is filtered through filter paper. and washed well with the organic solvent. When the zeolite particle is too small to use filter paper, a centrifuge is employed to separate the particles. The zeolite crystals are introduced into a reaction container containing toluene and then dispersed well by an ultrasonic washer. Said compounds also can be evaporated without solvent under reduced pressure to vacuum so as to combine with the substrate or zeolite.
5. Method for Forming a Pattern on the Surface of Substrate
Although there are many methods for the formation of a pattern on the substrate surface, the present invention employs the following three methods. xe2x80x9cFormation of a patternxe2x80x9d in the present invention means that the surface is blocked so that zeolite will react or will not react with the surface in a selective manner. The present method is not restricted on to the three methods, and any modifications or method that can give the same effects with those methods fall within the scope of the present invention.
First, there is a method wherein a UV ray is employed to modify linking compounds.
On a substrate to which linking compounds are combined, a pattern-formed photomask is put and then UV ray (254 nm) is irradiated for a suitable time. In the region to which a UV ray has been irradiated, said terminal functionality of the linking compounds that are combined onto the substrate will be modified. In the region to which a UV ray has not been irradiated, the terminal functionality of the linking compounds that are combined onto the substrate will still remain. Accordingly, a difference in the chemical functionality arises on the surface of substrate along the shape of the pattern. The change of the functionality by the irradiation of UV ray can be performed conversely.
Second, there is a method wherein blocking compounds or linking compounds are directly applied on the substrate in a microcontacting manner.
In the present invention, the blocking compound means a compound that has only one functional group which will react with the substrate, and as a result, does not have any functional group which will react with zeolite or the other linking compound at the opposite end. For example, it includes trialkoxyalkylsilane (RSi(OR)3, R=alkyl) or trichloroalkylsilane (RSiCl3, R=alkyl). In said blocking compound, alkyl group preferably has at least six carbon atoms, more preferably at least ten carbon atoms.
On a PDMA (polydimethylsiloxane) stamp on which a pattern has been formed, a solution of octadecyltrichlorosilane (OTS) in hexane is applied, and then said stamp is mounted on a spin coater. The PDMS stamp was rotated to uniformly distribute octadecyltrichlorosilane thereon and then impressed on a glass plate. The glass plate was left at room temperature for more than one hour and then dried at 120xc2x0 C. for five minutes. Octadecyltrichlorosilane reacts with silanol group of the glass to form an octadecyl monolayer along the shape of the pattern. Namely, an octadecyl monolayer is formed in the region of the glass surface with which the stamp had contacted, while silanol remains unreacted in the region of the glass surface with which the stamp has not contacted. When the surface of the glass plate on which octadecyl groups are combined in a pattern is treated with a linking compound as described above, the area wherein octadecyl groups are already combined will still remain as it is, while the linking compound is combined only to the region in which hydroxyl group (xe2x80x94OH) exists to give new functionality. Accordingly, the chemical functionality will be differentiated along the shape of the pattern.
Third, there is a method wherein a non-reactive metal is deposited on a part of the surface to block the metal-deposited surface. In general, any metal that can be applied in conventional chemical deposition may be employed in the present invention. The present invention exemplifies a deposition of platinum, to which the scope of the invention is not restricted.
By using the procedure that is similar to the method using a UV ray, a pattern-formed mask is put on the substrate and then platinum is deposited in a thickness of about 15 nm by means of a vacuum thermal depositing machine. The area contacted with the mask preserves the functionality of substrate without depositing platinum, while the exposed area is deposited with platinum to have the functionality of platinum. In this way, a pattern can be formed so that on the surface of substrate has diverse chemical functionality different from each other.
The method for forming a pattern on the surface of substrate with a linking compound or blocking compound is not restricted to the above methods only.
6. Method for Forming a Patterned Monolayer or Multilayer of Zeolite on the Surface of Substrate
When zeolite particles arc chemically combined with a pattern-formed substrate having a difference in its chemical functionality along the pattern, zeolite will combine along the pattern due to its functionality.
Meanwhile, zeolite particles may be physically attached on the patterned zeolite monolayer of a composite during the preparation thereof. These zeolite particles physically attached thereon can be easily removed by ultra-sonic washing.
A composite having a patterned zeolite multilayer can be produced easily by repeating said methods as described above. Specifically, a patterned zeolite bilayer (double layer) will be formed by repeatedly treating zeolite particles having a functional group capable of chemically reacting with the functional group of the linking compound which has already combined onto a patterned zeolite monolayer, and a patterned zeolite multiplayer will be formed by repeating the above procedure for the bilayer.
In a multilayer composite, the types of zeolite consisting of the upper and lower layers are the same as or different from each other, and the patterns of the upper and lower layers are the same as or different from the other.